Gas turbine engines produce power by extracting energy from a flow of hot gas produced by combustion of fuel in a stream of compressed air. In general, turbine engines have an upstream air compressor coupled to a downstream turbine with a combustion chamber (“combustor”) in between. Energy is released when a mixture of compressed air and fuel is burned in the combustor. The resulting hot gases are directed over blades of the turbine to spin the turbine and produce mechanical power. In a typical turbine engine, one or more fuel injectors direct some type of liquid or gaseous hydrocarbon fuel (such, diesel fuel or natural gas) into the combustor for combustion. This fuel mixes with compressed air (from the air compressor) in the fuel injector, and flow to the combustor for combustion. The compressed air, which may exceed 800° F. (426.7° C.) in temperature, may surround sections of the fuel injector, and may create a hot ambient environment for the fuel injector. Combustion of the fuel in the combustor can create temperatures exceeding 2000° F. (1093.3° C.). These high temperatures in the vicinity of the fuel injector increase the temperature of the fuel injector during operation of the turbine engine.
In fuel injectors, fuel lines are used to direct the fuel to the fuel injector, and fuel galleries direct the fuel through nozzles that deliver the fuel to the combustor. The high temperatures of the fuel injector during operation may lead to coking of liquid fuel in these lines and galleries. Over time, this coke deposit in the lines and galleries can lead to flow restrictions that adversely affect the operation of the gas turbine engine.
U.S. patent application publication US 2007/0157616 A1 to Hernandez et al. (the '616 publication) describes a fuel injector for a jet engine. The fuel injector of the '616 publication includes a primary fuel circuit and a secondary fuel circuit that direct separate streams of fuel through the fuel injector. The secondary circuit includes an annular distribution chamber positioned in an air swirler and fluidly coupled to a plurality of orifices. The primary circuit includes a separate distribution chamber that is positioned adjacent the distribution chamber of the secondary circuit. In the fuel injector of the '616 publication, fuel in the distribution chamber of one fuel circuit is used to cool the fuel in the distribution chamber of the other fuel circuit. The fuel injector of the '616 publication may be suitable for applications that include multiple fuel circuits positioned proximate each other. However, in applications where such a layout is not feasible due to space or other constraints, the fuel injector of the '616 publication may not be suitable. For instance, positioning multiple distribution chambers adjacent to each other in a single air swirler may introduce design complexities when space is limited.